Effect of Sc and Zr on Al<sub>6</sub>(Mn,Fe) Phase in Al–Mg–Mn Alloys

Abstract

The effects of Sc and Zr on the shape, size, and number density of Al6(Mn,Fe) phase in Al–5Mg–0.7Mn alloys were investigated by this article. The results showed that Sc and Zr can form strengthening particles of Al3Sc and Al3(Sc,Zr), which have the effect of refining grains and modifying the morphology and distribution of Al6(Mn,Fe) phase. The OM, SEM, and TEM images indicate that with the formation of primary Al3Sc and Al3(Sc,Zr), the shape of Al6(Mn,Fe) became more regular, size of Al6(Mn,Fe) became smaller, and the number density of Al6(Mn,Fe) increased when compared with base alloy. Zr could motivate the precipitation of primary Al3(Sc,Zr) and Al–5Mg–0.7Mn–0.2Sc–0.2Zr had better refining effect than Al–5Mg–0.7Mn–0.4Sc. The grain refinement and finely dispersed Al6(Mn,Fe) phase can improve the mechanical properties such as yield strength and ultimate tensile strength and the corrosion resistance by the results of intergranular corrosion (IGC) also improved.